The economy only works when everyone has money to spend. If 30% of the population is broke, that's going to cause a huge drop in economic activity. Most economic activity is driven by consumer spending.
Agreed. Current response plans won't handle 30% of the population being broke; if that happens something very different will be needed.
The way you fix that is by redistributing wealth. The government is doing this in a roundabout way by borrowing the money for a massive stimulus and recouping that money by increasing taxes on the wealthy later - likely with a Democrat administration so Republicans can maintain their rhetoric.